The goal of the proposed research is to develop potent and selective TBK1/IKKi dual inhibitors for the treatment of castration resistant prostate cancer (CRPC). Prostate cancer (PCa) is a heterogeneous malignancy that progresses from prostatic intraepithelial neoplasia to locally invasive adenocarcinoma to hormone-refractory carcinoma. Curative treatments are not available for hormone-refractory PCa. Recently, many studies suggest that the non-canonical IKKs, TBK1 and IKKi, play important roles in tumor growth and development. In preliminary studies we found that both p-TBK1 and p-IKKi were highly expressed in human advanced PCa and CRPC. We found that individual knockdown of either IKKi or TBK1 had minor effects on cell survival while simultaneous knockdown of both TBK1 and IKKi significantly inhibited cell proliferation. In mouse models, we found that knockout of either IKKi or TBK1 had minor effect on CRPC growth, while knockdown of both TBK1 and IKKi significantly suppressed CRPC development. These results suggest that both TBK1 and IKKi are essential for CRPC survival and development. Inhibiting either one alone is not enough to inhibit cancer cell proliferation due to the overlap and compensatory function between them. Thus, simultaneously targeting both TBK1 and IKKi is necessary for the efficient shutdown of cancer cell growth. Accordingly, we have developed several groups of compounds that exhibited high potency of TBK1/IKKi dual inhibition. Treatment of prostate cancer (and other cancers) cells with these compounds dramatically reduced cell proliferation rate. These TBK1/IKKi dual inhibitors also significantly suppressed the growth and development of CRPC in mouse models. Most importantly, these compounds have drug-like properties including low molecular weight, clean CYPs inhibition, and good microsomal stability. We will (1) investigate the anti-tumor efficacy and selectivity of TBK1/IKKi dual inhibitors, and (2) SAR optimization to obtain novel TBK1/IKKi inhibitors that are suitable for Investigational New Drug (IND)-enabling studies. Our studies will lead to development of novel strategies and highly efficient therapeutics for the treatment of human (prostate) cancer.